Bituminous paving.



V UNITED STATES PATENT OFFICE,

GEORGE P. HEMSTREET, 0F HASTINGS-UPON-HUDSON, NEW YORK, ASSIGNORTO THE INTERNATIONAL PAVEMENT COMPANY, OF HARTFORD, CONNECTICUT, A CORPORA- TION OF CONNECTICUT.

BITUMINOUS PAVING.

No Drawing.

To all whom it may concern:

Be it known that I, GEORGE P. HEMSTREET, a citizen of the United States, residing at Hastings-upon-I-Iudson, in the county of VVestchester, State of New York, have invented an Improvement in Bituminous Pavv -mg, of which the followmg description 15 a stone dust, which may be added to make up the required proportion; with an asphaltic binder or cement to unite the mass into 'a compact whole. In preparing this paving composition, as, for example, for block or tile purposes, the body material is commonly first heated and placed in a suitable mixer, usually the ordinary pug mill and is drymixed. Vhen thoroughly dry-mixed and while under agitation in the pug mill, the asphaltic cement, usually composed of one of the asphalts together with a proper percentage of residuum or other flux, is poured into the agitated mass and the whole thoroughly mixed until the surfaces of all the stony particles both coarse and fine, are completely coated with the icement. The entire mass is now conducted by suitable means to the press, in which it is compressed under heavy pressure intoblocks or tiles of the required dimensions. After the compressed blocks or tiles have been cooled, usually in running water, the sto 1y body materials thereof are found usuallyto be so'complet-ely united by the cement that a fracture of a block'will cause the fracture of the larger particles of stone, rather than the separation of the stony particles one from another by failure of the cement to hold them, It has been found in practice that the longer the mass remains in its compressed condition, the more completely does the cement become set. In compressing these blocks or tiles, the composition, which reaches the press in it takes so lon Specification of Letters Patent. Patented Aug. 15, 1911. Application filed February 18, 1905. Serial No. 246,333.

a granular heated condition, frequently varies in consistency, owing to changed conditions of temperature, moisture and the like, and results in a considerable percentage of seconds, or blocks that are more or less imperfect or under or over size. So also the repairs and renewals of pavements once laid result in the collection of a considerable quantity of partially worn blocks, defective because of their reduced sizeor broken corners, broken in removing or under exceptional trafiic but otherwise solid and enduring because the cement has become thoroughly and permanently set. Many attempts and much experiment have been made to utilize these damaged or old blocks, in the making of new blocks, and this experiment and effort has been justified because of the substantial results that would fiow therefrom. So far as known to me, however, all these efforts previous to mine have beenunsuccessful and for-the reason that no practicable way of reducing the blocks to a granular condition has been found. It has been found that the blocks cannot be heated in their full sized condition and thereby reduced for the reason that for the heat to penetrate to the interiors of the masses that the exterior portions become too soft and lose many of the lighter oils in volatilization. On the otherhand, it has been attempted to crush the blocks in crushing machines down to a degree of fineness substantially the same as when the stony particles were first introduced to the press but here it has been found that the finely crushed masses have presented so many new broken stony' faces to be recoated with cement that the whole amount of cement required in the new blocks would be abnormal and the resultant blocks unduly soft and uncommercial. I have discovered. however, that if the old or previously com pressed blocks be broken in a. crusher into small pieces, say measuring from one to two inches in diameter, that the amount of I broken stony surfaces thereby produced, is not sufficient to require an undue amount of cement in the ultimate mixture, yet when so reduced the masses may be passed through a stone heater and sufficiently and uniformly heated through and through so that when they issue from the heater they are in a granular condition and nearly though not quite as soft and flowable as the new mix:

' turej b'ut sufficiently so to enable the same to be'added in proper proportions to and mixed with the-new mixture in the pug mill and the whole thoroughlyintermixed and incorporated and afterward pressed as before into blocks or tiles. Of course thepropor- "tion of cement first. placed in thepugmill somewhat exceeds Whatwould be required if none of the old materials were to be incor- .porated therewith; this excess, being sufficient merely to coat the freshly broken stony handled properly.

In carrying outthis process extensively,

as I have, I have been able to use all. seconds or old-blocks, andthereby economize in the ultimate costof blocks suited for paving notwithstandingthe increased cost of handling the materials which results from the breaking and heating of the old blocks. I

have also found what is also of'importance, namely, that the blocks in which this old material isincorporated as above described,

are superior to blocks otherwise similarly "made but wholly of new materials; and this I attribute to the fact that the first compres-' sion of the' blocks followed by a certain period of set before they are again utilized, gives the binder opportunity more thoroughly and permanently to unite the stony particles in a permanent and enduring manner and that this permanency is not destroyed by the subsequent recrushing' and reheating, but softens merely to a sufiicient extent to enable it to be remixed with the new materialv without losing that intimacy and-permanency of binding effect which resulted from the first compression and subsequent'period of set. l Vhen subjected in the new mass to 'a further compression, this intimacy and permanency or cementitious union is rendered even more complete and the average for the block becomes higher v than asif wholly made, from new materials.

I In carrying out my inventionthe proportionsof the various elements employed may .be Varied as occasion may require." The following example has shown excellent results:

Take 85% more or less of freshly crushed and partly pulverized rock reduced to the fusual'sizes and mix the same with 41} to 5% more or less of limestone dust or fines, mix- '55 ing the whole thoroughly in a pug mill or suitable mixer; add to this from 11 to 12% v of asphaltic cement, which may be composed, for example, of the following elements. in the following proportionst' 100 lbs. of refined Trinidad Lake asphalt and 8 to 12 lbs. 'of residuum oil or other flux thoroughly'mixed and heated; this cement being added to and mixed with the dry-mixed material in the pug mill, and while still in the old materials prepared as ner and compressed into blocks or tiles or other articles for use.

described, and reduced to a granular condit10n, are ordmarlly not so moblle as the new mixture wlth which they are to be incorpoold will de end somewhat upon. the characreducing the blocks to such sizes'as may be readily penetrated by an'even degree of that is consistent with so doing.

Claims: 1 1. The improvement in bituminous paving for the utilization of previously compressed paring masses in a new mixture or ing the said masses into relatively small pieces approximately one to two lnCllQSlD comprising stony materials. fines and a cementitious binder, thoroughly mixed and heated, and compressing. the resultant "mixture for use. I

2. The improvement in the manufacture of paving compositions which'consists in heating a body material composed of stony materials and fines. dry mixing the same, adding thereto" and mixing therewith a cementitious binder, and compressing the mixture into blocks or tiles, cooling the blocks or tiles so formed, permitting said blocks 'or tiles to set, breaking the same into smaller pieces exceeding the size produced by grinding or pulverizing, said pieces substantially retaining the permanent union of their stony particles and binder, heating said pieces together uniformly throughout, mixing the same with a fresh batch of the said mixed, heated and-uncompressed commixed mass for use. v

3. The improvement in the manufacture of paving compositions which consists in heating a body composed of stony materials, adding fines including limestone dust,1mixing the same, adding a bituminous cementitious binder,.a-nd compressing the mixture tiles so formed, permitting said blocks or The old materials when reheated as above ter' of the ieating apparatus employed and also 'uponthe sizes to which the old blocks have been first reduced before the heating,v Probably the best results are obtainable by heat,while reducing the number of frac-U tures.of the stony material to a minimum diameter or through dimension, heating the pieces so formed, mlxing them wlth a batchv of fresh bituminous pav ng composition position and compressing the thoroughlytiles to set, breaking the same into smaller 1 above stated are added to the mass inthe proportion say of 1 of the old to 4 of the 1 I new. After the whole has been thoroughlymixed together, it is removed in usual mane.

rated and therefore the proportion in which the old can be added to the new, will "vary. more or less, according to ".themobility of the old. For'exaniple: this mobility of the paving composition which consists in reducinto blocks ortiles, cooling the blocks or said mixed, heated and uncompressed composi'tion and compressing the thoroughly mixed mass for use.

4. The improvement in the manufacture L of paving composition which consists in heating a body composed of stony materials, adding fines including limestone dust, mix ing the same, adding a bituminous cementitious binder, and, compressing the mixture into blocks or tiles, cooling the blocks or tiles so formed, breaking the same into smaller pieces exceeding the size produced by grindmg or pulverizmg, said pieces substantially retaining the permanent union of stony particles and binder,'heating said pieces together uniformly throughout, mixing the same with a fresh batch of-the said mixed, heated and uncompressed composition and com )ressing the thoroughly mixed mass into briciis or tiles for use.

5. The improvement in bituminous pav ing for the utilization of previously compressed paving masses in a new mixture or composition which consists in reducing the said masses into relatively small pieces, approximately one or two mches in diameter or through dimension, heating the pieces so formed, heating and mixing a batch of freshly crushed and partly pulverized rock, limestone dust and asphaltic cement, agitating said batch, mixing therewith said relatively small pieces of previously compressed paving masses, and compressing the resultant mixture for use.

6. The improvement. 1' bituminous paving for the utilization of previously compressed paving masses in a new mixture or composition which consists in reducing the said masses into relatively smah pleces, ap-

proximately one or two inches in diameter or through dimension, heating tliepieces so formed, heating and mixing a batch of freshly crushed and partly pulverized rock, fines and a somewhat excessive quantity of cementitious binder and while the said batch in agitation, adding thereto said relatively small pieces of previously compressed paving masses and cbmpressing the resultant mixture for use.

7. The improvement in bituminous paving for the utilization of previously compressed paving massesin a new mixture or composition zvhich consists in reducing the said masses into relatively small pieces, approximately one or two through dimension, formed, heating and mixing heating the pieces so a atch oi inches in diameter or t l l through dimension,

freshly crushed and partly pulverized rock, limestone dust and a somewhat excessive quantity of asphaltic cement and, while the said batch is in agitation, adding thereto said relatively small pieces of previously compressed paving masses and compressing the resultant mixture for use.

8. The improvement in bituminous paving for the utilization of previously compressed paving masses in a new mixture or composition which consists in reducing the said masses into relatively small pieces, approximately one -or two inches in diameter or heating the pieces so formed, heating and dry mixing a batch of freshly crushed and partly pulverized rock and fines, adding to and mixing therewith a somewhat excessive quantity of cementitious binder and, while the said batch is in agitation, adding thereto said relatively small pieces of previously compressed pavmg masses and compressing the resultant mixture for use.

9. The improvement in bituminous pav ing for the utilization of previously compressed paving masses in a new mixture or composition which consists in reducing the said masses into relatively smallpieces, appro; ately one or two inches in diameter or through dimension, heating the pieces so formed, heatin and dry mixing a. batch of freshly crushe and partly pulverized rock and a small proportion of limestone dust, adding to and mixing with said batch a somewhat excessive quantity of cementitious binder, and whilethe said batch is in agitation adding thereto a less quantity of said relatively small pieces of previously compressed paving masses, and finally compressing the-resultant mixture for use.

10. The improvement in the manufacture of bituminous paving which consists in compressing the desired'mixture into relatively large masses, such as paving blocks or tiles, permitting them to set in such condition, re ducing the same to relatively small pieces or lumps while maintaining the permanent union of the binder and stony particles of the said relatively small pieces or lumps, heating the same, thereby reducing the same to a granular condition, mixing the granular iaterial thus obtained with a fresh and Pl't iously uncompressed material and finally compressing the whole for use.

In testimony whereof. I have signed' my name to this specification, in the presence of two subscribing witnesses.

GEGRGE P. HEMSTREET.

Witnesses HARRY Srncnrnr, Fern Gonnrcrr. 

